Insights into Brain Injury

Scientists have uncovered new details about what happens in the brain after a concussion. The findings point to possible ways to reduce the harmful effects of these injuries.

Concussions are a mild type of brain injury. They can arise after a swift blow to the head. Concussions are rarely life-threatening, but they can have serious and lasting effects.

NIH researchers have been studying people who suffered a concussion but had “normal” CT scans that showed no signs of brain damage. The scientists used a special type of MRI and found that fluid was leaking into the thick outer covering of the brain in nearly half of 142 patients with concussions.

To take a closer look, the researchers developed a way to visualize the effects of mild brain injuries in mice. The scientists initially saw cell death in the brain’s outer covering and in a thin layer at the brain’s surface. Cell death in the underlying brain tissue began 9-12 hours after injury.

When the thin surface layer breaks down, harmful molecules can get into the brain. Within an hour after head injury, the researchers saw specific cells acting to repair the damage. These reactions, never before seen in living brains, help to secure the brain’s protective barrier.

Immediately after brain injury, high levels of cell-damaging molecules appeared at the trauma site. Certain compounds can reduce levels of these molecules. When the researchers applied one such compound directly to the skull bone 15 minutes after brain injury, cell death dropped by 67%. When it was applied 3 hours after injury, cell death fell by 51%.

“This idea that we have a time window within which to work, potentially up to 3 hours, is exciting and may be clinically important,” says study leader Dr. Dorian McGavern of NIH. However, “humans have a thicker skull bone, and so we would need to evaluate whether the same technique could apply to the human skull bone.”